The trial is being conducted by researchers at the Mood Disorders Unit at Sydney's Prince of Wales Hospital. Psychiatrist Dr Colleen Loo said that although TMS is still considered an experimental treatment, it shows promise.

"There have been about 25 studies, with about 600 people involved, and most of those have found that TMS does work in depression," said Dr Loo. "What we're trying to do now is see if we can make it more effective."

Patients remain fully awake during the procedure, and so far there have been no reported side effects.

While antidepressant medication and therapy are effective for many people with depression, they do not work for everybody.

"Our hope is that TMS may be a suitable treatment for people who don't respond well to current treatments," said Professor Philip Mitchell of the University of New South Wales, Director of Research at the Mood Disorders Unit.

Results are expected in six months.

Meanwhile, a study published yesterday in a special supplement to the Medical Journal of Australia reveals that 60 per cent of patients visiting Australian GPs suffer some form of depression.